Development And Testing Of Pipeline Stress Detection System Based On ACSM

Stress concentration is the main way causing early pipeline failure,which can lead to pipeline deformation and cracking.As a result,the pipeline structure is failure causing oil and gas leakage accidents.Aiming at the demand of oil and gas pipeline stress detection,the alternating current stress measurement(ACSM)technique is studied in this paper.The pipeline force magnetic coupling theory model is set up.The stress changes and the mapping relationship between induction electromagnetic field is analyzed.The different stress state on the influence law of characteristic signal is studied using the numerical simulation model.According to the characteristics of pipelines,the stress testing probe,hull and multi-function testing software are developed to form a complete ACSM pipeline stress testing system.The pipeline stress testing experiment is carried out.This system finally realizes the judgement and early warning of pipeline stress concentration area.The method and system can provide theoretical and technical support for the early diagnosis of oil and gas pipelines,which has a certain engineering application value.The main contents of this paper include the following aspects:(1)Establishment of pipe-force and magnetic coupling theory and simulation modelBased on the basic principle of the ACFM technology,the coupling model of pipe force and magnetic field is built combined with the basic theory of magnetic domain and piezomagnetic effect.The change law of the related magnetic parameters in ferromagnetic crystal is emphatically studied under the joint action of stress and external magnetic field.The sensitivity of triaxial magnetic field signals to stress is analyzed.The characteristic signal of stress detection is selected.The influence mechanism of external excitation direction,external stress form and other factors on the characteristic signals is explored to provide a theoretical basis for subsequent research.(2)Design of pipeline stress detection hardware systemAccording to the results of the simulation and the demand of the pipeline detection,the pipeline stress testing plan is set up.The layout of the transducer is optimized.The applicability pipeline stress testing probe is designed.According to the actual working condition,the testing module of signal producing module,signal conditioning module,signal transmission module are selected and designed to set up the piping stress testing hardware system.(3)Research on pipeline stress assessment method and software developmentAccording to the ACFM stress detection theory and the field pipeline stress detection condition,the original Bx signal is filtered to remove the interference signals caused by noise,jitter and lifting,etc..The pipeline stress signal is highlighted based on the Envelope Function Envelope method.Based on the Labview software platform,the pipeline stress detection software is developed.Finally,a complete pipeline stress detection system is set up.(4)Stress detection system testing and data analysisStress detection experiments are conducted,including tensile machine flat tensile test,radial pressure test of large diameter pipeline,axial tensile test of pipeline test bench and field traction test.The characteristic signal change rules are studied under the condition of radial force and axial force applied by pipeline to verify the simulation rule.The influence of speed on the signal is studied.The characteristic signals are obtained to identify the stress in the pipeline.The practicability and stability of the whole system are verified by field testing of pipe stress,which laies a foundation for the industrial application of the prototype.